The different types of Boiler... Boilers differ in size and shape -  such as floor standing, wall mounted or situated inside a fireplace. The most important difference is the way they produce hot water for washing, bathing and showering. Traditional boilers and system boilers heat water in a storage cylinder typically sited in an airing cupboard. Combination boilers heat water instantaneously (via a special heat exchanger inside the boiler) only when you turn on a hot tap.

Traditional Boilers are available in a wide range of designs and outputs to suit almost any need. Back boilers save space by sitting inside a fireplace and are cost effective like-for-like replacements. However, due to recent legislation changes, we must always look to replace these boilers with a new high efficiency condensing boiler and it is in only unusual circumstances that a back boiler will be replaced with another back boiler. Wall mounted boilers can be small enough to fit inside a kitchen cupboard and still be powerful enough for the larger property. A traditional or system boiler (one with some system components built into the case) can deliver lashings of hot water to several taps simultaneously. You need space for a cylinder as well as a boiler but modern versions are surprisingly compact. You also have to anticipate you hot water need but modern controls make it easy to plan around your daily./weekly routine and the new generation of 'high recovery' cylinders are designed to cater for unexpected demand.

Combination Boilers heat water instantaneously whenever you open a hot tap obviating the need for a storage cylinder. Cold water is piped direct from main supply which does away with the need for a water tank in the loft. In Summer, there's often a delay until it reaches working temperature but the supply is endless. The temperature at the tap is dependant on the temperature of the mains supply and flow rate. In Winter, the delivery of usefully hot water can be very limited - perhaps taking two or three times longer to fill a bath than a traditional system - and simultaneous demand by a shower and, say, a washing machine can result in a trickle at each. The latest models feature high outputs, small stores or pre-heating systems designed to supply more hot water with minimal delay in order to avoid wasting water.

Unvented Hot Water Systems comprise unvented cylinders which are storage water heaters connected directly to the main water supply. This dispenses with the need for water storage tanks in the roof and results in high pressure hot and cold water to all outlets, including showers, without the need for a pump.